(1) Field of the Invention
The present invention relates to a compound useful as a novel recording material for optical discs and a near infrared-absorbing agent which can play an important role in optoelectronics fields of information recording, display sensors, protective spectacles and the like; an optical recording medium such as an optical disc or an optical card in which the compound is contained in a recording layer; and a near infrared-absorbing agent comprising the compound.
(2) Description of the Related Art
Techniques for utilizing phthalocyanine dyestuffs in recording layers of recording media such as optical discs and optical cards are widely known by Japanese Patent Application Laid-open Nos. 154888/1986 (EP 18646), 197280/1986, 246091/1986, 39286/1987 (U.S. Pat. No. 4,769,307), 37991/1988 and 39388/1988, but the phthalocyanines disclosed in these publications have been insufficient as the recording media from the viewpoints of sensitivity, refractive index, recording properties and the like. A compound in which they have been improved is described in Japanese Patent Application Laid-open No. 62878/1991, but this compound is still poor in recording properties at the time of writing by a laser beam, and so it is not sufficiently practical yet. Furthermore, it is disclosed in Japanese Patent Laid-open Nos. 214388/1992 and 238150/1993 that a phthalocyanine in which fluorine is introduced into a substituent is excellent in solubility and adhesive properties to a resin, but the introduction of the fluorine group does not contribute to the improvement of the sensitivity at the time of the writing by the laser beam.
The above-mentioned phthalocyanines do not have sufficient performances regarding sensitivity (a C/N ratio or an optimum recording power), reflectance, recording properties (the shape of a signal at recording) and the like.